Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

252
FXUS63 KLOT 132338
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
638 PM CDT Fri Mar 13 2026

.KEY MESSAGES...

- Gusty winds will abate this evening.

- There is about a 20% chance for some areas to pick up a
  dusting of snow Saturday morning.

- Waves of thunderstorms may occur on Sunday. There is a Level
  2 out of 5 threat for severe thunderstorms Sunday afternoon
  east of Interstate 55. The primary threat is damaging winds.

- A period of accumulating snow accompanied by northwesterly
  winds gusting over 40 mph may occur Sunday night into early
  Monday.

- A period of cold temperatures is expected Monday and Tuesday,
  with overnight wind chills ranging from 0 to 15 below,
  especially Tuesday morning.

- The period of cold temperatures should be brief with warming
  temperatures by the end of next week.

&&

.DISCUSSION...
Issued at 249 PM CDT Fri Mar 13 2026

Through Saturday:

A strong pressure gradient, associated with deep low pressure
moving across northern Lower Michigan, continues to support
damaging westerly wind gusts of 50 mph to occasionally as high as
60 mph across northern IL into northwestern IN. Overall, expect
these speeds to gradually ease through the mid and late afternoon
hours as the area of low pressure continues eastward. The current
High Wind Warning is set to end at 4 PM this afternoon. However,
we may soon be able to convert this warning to a Wind Advisory
for the remainder of the afternoon, but I would like to see peak
hourly wind gusts drop below 55 mph before doing so. Either way,
expect wind gusts to gradually ease into early this evening,
before becoming light and variable tonight as a surface high
shifts overhead.

Tonight into Saturday, a sharp west-northwest to east-southeast
oriented baroclinic zone will become draped right across our
region in the wake of today`s Great Lakes storm system. This will
set the stage for bands of strengthening low-to mid-level
frontogenesis across our area on Saturday in response to an
increasing southerly mass wind response to the next major storm
system taking shape across the Plains. Consequently, this may
induce some developing bands of snow that slide northward across
our area through the day Saturday. However, much of this activity
may end up as virga due to lingering low-level dry air.
Nevertheless, there is about a 20% chance for some light snow
Saturday, though with temperatures warming into the low 40s in the
afternoon, we don`t expect any real travel impacts.

KJB


Saturday Night through Friday:

A deepening trough is expected to be digging into the central
Plains Saturday night with a surface low developing leeward of
the Rockies. As the low develops, strong warm advection will
begin to materialize ahead of the low across MO, IL, and IN
which will push the baroclinic zone over IL and IN northward as
a warm front. Last forecast trends continue to show the warm
front lifting well into southern WI by Sunday morning which
should keep the band of precipitation forecast to develop along
it north of our area. However, a few rain and/or snow showers
(20-30% chance) may be seen Saturday night near the IL-WI line.
Otherwise, Saturday night should largely be precipitation free
with just gradually warm temperatures through the night and
breezy southeast winds gusting around 20 mph.

Heading into Sunday, the surface low will begin to lift into
the Mississippi Valley and western Great Lakes continuing to
deepen as it does so. The combination of diffluent flow aloft,
the approaching surface low, and warm advection will generate a
lot of synoptic ascent across northern IL and northwest IN on
Sunday which should be more than sufficient to generate
scattered showers and thunderstorms, especially along and south
of I-80 where the greatest moisture and instability is forecast
to be present. Latest forecast soundings with the 12z guidance
suite have actually come in with more mid-level capping due to
the warming temperatures aloft which looks to keep the
instability more of a limiting factor. However, given the
aforementioned forcing suspect that some of this capping will be
overcome and allow a broken line of showers and thunderstorms
to develop ahead of the cold front Sunday afternoon. Couple
these ingredients with the 40-50 kts of shear in place and
conditions continue to look favorable for a few strong to severe
thunderstorms to develop as well. With the more limited
instability it appears the main threat with any severe storms
will be damaging winds in excess of 60 mph, but with the veering
low-level wind profiles a few tornadoes cannot be ruled out.
For these reasons a marginal risk (level 1 of 5 severe threat)
remains for most of northern IL with a slight risk (level 2 of 5
severe threat) for areas east of I-55.

The surface low will move overhead Sunday evening and drag a
cold front into and eventually through the area Sunday night
which will bring the severe threat to a close by 8-9 PM Sunday
evening. behind the front, temperatures are forecast to quickly
cool overnight which will transition the rain over to snow from
west to east Sunday night. While there remains a chance (10-15%)
for a period of freezing rain and sleet to develop as
temperatures cool, there continues to be some uncertainty as to
how quickly temperatures will cool aloft and thus have just
opted to maintain a rain/snow mix mention in the forecast during
this period. Once snow begins it is expected to prevail through
the day on Monday as the system`s deformation band slides
through the area. With temperatures on Monday forecast to be in
the 20s snow accumulations are expected to occur, but there
continues to be some uncertainty in snow rates and amounts. The
latest thinking is that snow accumulations would generally be in
the 2-4 inch range (60-80% chance) for this event with the
highest amounts forecast to occur north of I-80 and in northwest
IL. However, there remains a 15-20% chance for localized
amounts upwards of 6 inches to occur.

Regardless of the snow amounts, the main concern with wintry
side of this system will be the threat for blowing and drifting
snow as gusty northwest winds develop behind the low. With wind
gusts expected to be in excess of 40-45+ mph Sunday night into
Monday any falling snow will be blown around and if snow can be
"fluffed" up enough as temperatures cool then some drifting snow
may also materialize leading to hazardous travel. Given that
there is still uncertainty in snow amounts, rates, and character
we have opted to hold off on issuing a Winter Storm Watch with
this forecast package. Though if trends continue then a
consideration for a winter weather headline will be needed with
future forecasts.

While snow will gradually taper Monday evening as the low and
associated trough shift east of the region, the upper pattern
will remain in a northwest flow regime. This regime will keep
much colder temperatures in play through Tuesday with overnight
lows in the single digits and teens with wind chills forecast to
dip below zero especially Monday night. Additionally, this
pattern will also put northern IL and northwest IN in a
favorable spot for clipper systems to brush the area and bring
us more chances for precipitation. The first of these clippers
is forecast to move through Tuesday night into Wednesday which
currently looks to fall mainly as snow, but there is some
uncertainty as to the coverage and intensity of any
precipitation locally. Otherwise, the upcoming week looks
somewhat tranquil with just moderating temperatures through the
week until our next chance at some precipitation arrives late
week into next weekend.

Yack

&&

.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 638 PM CDT Fri Mar 13 2026

WNW winds gusting around 30 knots at TAF issuance will veer NW
while diminishing this evening, with gusts under 15 knots by
midnight. Winds at around 5 knots will then slowly veer from NW
to ESE overnight through late Saturday morning. The shift from
NNW to NNE should occur around 12Z. Winds will remain ESE
through the evening, with gusts over 20 knots developing by
around sunset.

Coverage of low-end VFR clouds may slowly increase tonight
while gradually lowering into high-end MVFR levels. Have
maintained FEW/SCT coverage tonight and Saturday, but a brief
period of shallow BKN MVFR ceilings cannot be ruled out late
morning into the afternoon. Additionally, SN from a mid-level
cloud deck (bases around 10kft) midday may survive a layer of
dry air and seed the shallow MVFR clouds with VFR -SHSN. Chances
under 30 percent are too low to include in the TAF at this
time.

Kluber

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Gale Warning until 10 PM CDT this evening for the IL and IN
     nearshore waters.

&&

$$

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